util-ex v2.1.0

util-ex

Enhanced utils

This package modifies and enhances the standard util from node.js

API

Full API Documents is here: Docs

inject

▸ inject(aOrgFunc, aBeforeExec, aAfterExec): Function

Wraps a function and executes code before and/or after the wrapped function.

Throws

If aAfterExec is not a function and an error occurs while executing the wrapped function.

Example

import { inject as injectFunc } from 'util-ex'

// Wrapping a function with injectFunc
const originalFunc = (a, b) => a + b;
const beforeFunc = (a, b) => console.log(`Before execution: a = ${a}, b = ${b}`);
const afterFunc = (result) => console.log(`After execution: result = ${result}`);
const wrappedFunc = injectFunc(originalFunc, beforeFunc, afterFunc);
const result = wrappedFunc(1, 2); // Logs "Before execution: a = 1, b = 2" and "After execution: result = 3"

Example

// Wrapping a function with injectFunc and modifying arguments and return value
const Arguments = injectFunc.Arguments
const originalFunc = (a, b) => a + b;
const beforeFunc = (a, b) => {
  console.log(`Before execution: a = ${a}, b = ${b}`);
  return new Arguments([a * 2, b * 3]);
};
const afterFunc = (result, isDenied) => {
  console.log(`After execution: result = ${result}, isDenied = ${isDenied}`);
  return result * 2;
};
const wrappedFunc = injectFunc(originalFunc, beforeFunc, afterFunc);
const result = wrappedFunc(1, 2); // Logs "Before execution: a = 1, b = 2", "After execution: result = 6, isDenied = false"
console.log(result); // Output: 12

Example

// Wrapping a function with injectFunc and not executing the original function
const originalFunc = (a, b) => a + b;
const beforeFunc = (a, b) => {
  console.log(`Before execution: a = ${a}, b = ${b}`);
  return "Not executing original function";
};
const afterFunc = (result, isDenied) => {
  console.log(`After execution: result = ${result}, isDenied = ${isDenied}`);
  return "Modified return value";
};
const wrappedFunc = injectFunc(originalFunc, beforeFunc, afterFunc);
const result = wrappedFunc(1, 2); // Logs "Before execution: a = 1, b = 2", "After execution: result = Modified return value, isDenied = true"
console.log(result); // Output: "Modified return value"

Example

// Wrapping a function with injectFunc and getting the original function's error
const originalFunc = () => {
  throw new Error("Original function error");
};
const beforeFunc = () => {
  console.log("Before execution");
};
const afterFunc = (result, isDenied) => {
  console.log(`After execution: result = ${result}, isDenied = ${isDenied}`);
};
const wrappedFunc = injectFunc(originalFunc, beforeFunc, afterFunc);
wrappedFunc(); // Logs "Before execution", "After execution: result = [Error: Original function error], isDenied = false"

inject Parameters

inject Returns

Function

A new function that wraps the original function.

BeforeExec: If aBeforeExec is a function, it will be called with the same context and arguments as the wrapped function.

• If it returns an Arguments object, the wrapped function will be called with the modified arguments.
• If it returns a value other than undefined, the wrapped function will not be called and this value will be returned as result instead.

AfterExec: If aAfterExec is a function, it will be called with the same context, arguments with additional the result of the aOrgFunc and isDenied flag.

• If the aOrgFunc throws an error, the result parameter will be an Error object.
• If aAfterExec returns a value, it will be used as the final result of the wrapped function.
• If isDenied parameter is true, it means aOrgFunc was not called during execution of the wrapped function.

injectMethod

▸ injectMethod(aObject, aMethodName, aNewMethod): boolean

Injects method into an object. optionally preserving access to the original method via "super" and original instance via "self".

Note:

• In the new method, you can use this.super() to call the original method, this.super() is already bound with original instance.
• The this[aMethodName] is also the original method, but not bound yet.
• this.self is the original instance!

Example

import { injectMethod } from 'util-ex'

var obj = {
  method1: function() {
    console.log('Hello');
  }
};

var newMethod = function() {
  this.super();
  console.log('World');
};

injectMethod(obj, 'method1', newMethod);

obj.method1(); // Output: Hello\nWorld

injectMethod Parameters

injectMethod Returns

boolean

whether the injection is successful.

newFunction

newFunction(name, arguments, body[, scope[, values]])
newFunction(functionString[, scope[, values]])

Creates a new function with the given name, arguments, body, scope and values.

• If only one argument is provided and it is a function, returns a new function with the same code.
• If only one argument is provided and it is not a function, returns a new empty function with the given name.
• If multiple arguments are provided, creates a new function with the given name, arguments and body.

import { newFunction } from 'util-ex'

var fn = newFunction('yourFuncName', ['arg1', 'arg2'], 'return log(arg1+arg2);', {log:console.log})
newFunction('function yourFuncName(){}')
newFunction('function yourFuncName(arg1, arg2){return log(arg1+arg2);}', {log:console.log})
newFunction('function yourFuncName(arg1, arg2){return log(arg1+arg2);}', ['log'], [console.log])

//fn.toString() is :
/*
 "function yourFuncName(arg1, arg2) {
    return log(arg1+arg2);
 }"
*/

defineProperty

defineProperty(object, key, value[, aOptions])

Define a property on the object. move to inherits-ex package.

usage

const defineProperty = require('util-ex/lib/defineProperty')

let propValue = ''
const obj = {}

defineProperty(obj, 'prop', 'simpleValue')
defineProperty(obj, 'prop', undefined, {
  get() {return propValue}
  set(value) {propValue = value}
})